Honeywell Venturi tube VMU185A1009

The Honeywell Venturi tube VMU185A1009 is a gas and air mixing component designed for premix burners with a maximum capacity of 185 kW. It enables smooth modulation of the burner down to 17% of its maximum load by adjusting the fan speed, while maintaining a fixed 1:1 gas-to-air ratio. The venturi creates a controlled pressure drop that draws the correct proportion of gas into the combustion air stream, ensuring stable mixture quality across the modulation range. It is intended for use with a fan and a Honeywell gas regulating valve that provides the 1:1 ratio.

Venturi tubes of this type are selected primarily by their kW rating, which must match the burner's maximum output. Before ordering, verify that the venturi's dimensions and connection pattern fit the existing assembly, as no specific boiler or burner compatibility is stated. During installation, ensure the internal profile is free of burrs, grease, or dirt, and inspect mating flanges or o-ring seals for wear.

If a venturi tube is contaminated or damaged, the pressure drop changes, upsetting the air-fuel mixture and causing incomplete combustion or flame instability. A venturi with too low a rating may choke the flame, while one rated too high can lead to poor mixing. Check the internal profile for debris or damage and inspect seals for wear if burner performance degrades.